Nautilus

[Sarah]

The only existing genus of tetrabranchiate cephalopods. Aboutfour species are found living in the tropical Pacific, but many otherspecies are found fossil. The shell is spiral, symmetrical, andchambered, or divided into several cavities by simple curvedpartitions, which are traversed and connected together by acontinuous and nearly central tube or siphuncle. See Tetrabranchiata.

[Sarah]

to work out in a gym (eponymously after the Nautilus chain of fitness centers)